Dr. Anthony Fauci, the nation’s top infectious disease expert, on Tuesday criticized what he described as “outdated” information in AstraZeneca’s U.S. vaccine trial as “unfortunate” and acknowledged concerns with accuracy could lead to problems getting more Americans to take the vaccine. “It really is unfortunate that this happened. This is really what you call an unforced error because the fact is this is very likely a very good vaccine,” Fauci told ABC’s Robin Roberts “Good Morning America.” He added, “This kind of thing does … really cast some doubt about the vaccines and maybe contribute to the hesitancy. It was not necessary.”

The AstraZeneca vaccine has not yet been authorized in the United States. Early Monday, the company announced promising data in a press release, saying its vaccine had a 79% efficacy rate and was 100% effective in preventing severe disease and hospitalization.

But an independent group tasked with overseeing the company’s trial data, the Data and Safety Monitoring Board, notified Fauci’s National Institute of Allergy and Infectious Diseases (NIAID) that it was concerned by the data as portrayed in the press release, saying it may have provided an incomplete view of the vaccine’s efficacy.

“They felt that the data that was in the press release were somewhat outdated and might, in fact, be misleading a bit, and wanted them to straighten it out,” said Dr. Fauci.

In the early hours of Tuesday morning, the NIAID then released a statement advising the company to immediately review and update its data.

“DSMB expressed concern that AstraZeneca may have included outdated information from that trial, which may have provided an incomplete view of the efficacy data,” the agency said. “We urge the company to work with the DSMB to review the efficacy data and ensure the most accurate, up-to-date efficacy data be made public as quickly as possible.”

The questions over AstraZeneca’s data come as its vaccine was temporarily suspended in some European countries after reports of blood clotting in some vaccine recipients, though the company says its U.S. and Latin America-based trial uncovered no such safety issues.

But the independent monitoring board took issue with the company’s claims about the vaccine’s efficacy — not its safety. AstraZeneca released a statement in response and said the data included cases up to Feb. 17, but that it continues to analyze cases that have occurred since then. Those additional illnesses among trial participants could alter the final efficacy numbers for this vaccine.

“We have reviewed the preliminary assessment of the primary analysis and the results were consistent with the interim analysis” the company said in a statement. “We will immediately engage with the independent data safety monitoring board (DSMB) to share our primary analysis with the most up to date efficacy data.”

AstraZeneca is promising an update within 48 hours after their data analysis review.

But Fauci insisted that Americans shouldn’t worry about discrepancies with the data because there are safeguards in place, and that the FDA will ultimately review it, independent of the information AstraZeneca presents.

“They [the FDA] will independently go over every bit of data themselves and not rely on any interpretation from anyone including the company,” Fauci said. “So, that’s one thing that the American public should realize and probably the global public also that our FDA independently goes over that data, so that’s something you don’t need to be worried about.”